Supersensitized direct positive photographic silver salt emulsions

ABSTRACT

The light-sensitivity of a photographic material containing at least one direct positive silver salt emulsion layer the silver salt grains of said emulsion contain electron traps, can be improved by adding a sensitizing dye capable of being supersensitized, and in addition a supersensitizing styryl dye.

United States Patent Moisar et al.

[ 1 May 27, 1975 SUPERSENSITIZED DIRECT POSITIVE PHOTOGRAPI-IIC SILVERSALT EMULSIONS Inventors: Erik Moisar, Cologne; Oskar Riester,Leverkusen, both of Germany Assignee: Agfa-Gevaert Aktiengesellschaft,

Leverkusen-Bayerwerk, Germany Filed: Dec. 18, 1972 Appl. No.: 316,048

Foreign Application Priority Data Dec. 22, 1971 Germany n 2163676 US.Cl. 96/126; 96/129', 96/107;

96/108 Int. Cl. ..G03c1/10;G03c l/24; G03c l/26 Field of Search 1.96/108, 101, 126, 129

References Cited UNITED STATES PATENTS 9/1945 Mareis 96/126 2,423,7107/1947 Knott 96/126 2,533,426 12/1960 Carroll et al 96/126 3,501,3063/1970 Illingsworth .1 96/101 3,501,311 3/1970 Lincoln et a1 96/1013,772,033 11/1973 Ficken et a1 1, 96/126 OTHER PUBLICATIONS Moisar etal., Bunsenges Phys. Chemie 67, 1963, 356-359.

Gilman, Jr.; Photographic Science and Engineering, Vol.12,10/68.pp.237239.

Primary Examiner-Ronald H. Smith Assistant Examiner-J. P. BrammerAttorney, Agent, or Firm-Connolly and Hutz 4 Claims, 25 Drawing Figuresmgmgn m 27 ms 3; 885; 972

SHEET 1 FIG. 1 l J FIG. 2

FIG. 3

PATEI'HEBWEY ms 3.8851972 SHEET 2 PATENTEDHAYZT ms 3885972 SHEET 3 I."If: p

FF: C .00

FIG 9 e00 500 no I l L PATENTEUMAYZ? ms 3885372 SHEET 4 PATENTEIJMAYZYm5 3.885; 972

SHEET 7 700 500 500 LOG FIG 27 PATENTEUMAYZ! ms 3.885372 SHEET 8 FIG. 24soo 500 1.00

1 SUPERSENSTTIZED DIRECT POSITIVE PHOTOGRAPHIC SILVER SALT EMULSIONSThis invention relates to a photographic material with at least onespeetrally sensitized direct positive silver salt emulsion layer whichcontains substances with a super-sensitizing effect.

The sensitizing effect ol sensitizers in silver halide emulsions can beenhanced by the addition of certain compounds which do not themselvesabsorb light in the spectral region in question and are therefore notsensitizers. it is known that when the exposure of a photographicemulsion to light. in the absorption range of the sensitizing dyeadsorbed on the silver halide. is carried out in the presence of thecompounds known as supersensitizers. the photoconductivity in the silverhalide is increased and hence the formation of a latent image ispromoted. It is. however, also known that supersensitizers are effectivepositive hole traps and are therefore capable of suppressing theoxidation of latent image nuclei by the positive hole of the dye presentafter the act of sensitization (P. B. Gilman .lr.. Phot.Sci.Eng. 12(1968). 230). Both mechanisms give rise to increased formation of latentsilver nuclei and explain the increase in sensitivity of photographicnegative emulsions.

ln contradistinction to the mechanism in negative emulsions. themechanism in photographic direct re versal emulsions is based on theimagewise destruction of the developable fog nuclei by the positiveholes produced on exposure to light. Such direct reversal emulsions havebeen known for a long time. In order to prevent the competing formationof latent image nuclei on the crystal surfaces of such direct-reversalphotographic emulsions and to ensure that the positive holes which causeimagewise destruction of the superficial fog nuclei are not eliminatedby electrons. these emulsions may be provided with electron acceptors.eg with electron traps in the interior of the silver halide crystals orwith desensitizers situated adsorptively on the surface, the sensitivitybeing thereby increased (E. MOISAR and S. WAGNER. Ber. Bunsenges. Phys.(hemie 67 (N63) 356). In principle. these direct reversal emulsions makeuse of the solarisation effect.

It is among the objects ofthis invention to provide direct positivephotographic silver salt emulsions which have increased sensitivity tolight.

We now have found a photographic material contain ing at least oneoptically sensitized direct positive siiver salt emulsion layer thesilver salt grains of said emulsion contain electron traps in which thesilver salt emulsion has been sensitized with optical sensitizing dyeswhich are capable of being supersensitized and contains supersensitizingstyryl compounds.

Any spectral sensitizers capable of being supersensitized can be usedfor the emulsion according to the invention. Compounds of this kind havebeen described eg by F. M. HAMER in "The Cyanine Dyes and relatedCompounds. lnterseience Publishers a division of John Wiley and Sons.New York. 1964.

Symmetrical or asymmetric cyanine dyes of the following formula:

have proved to be particularly suitable. In the above formula,

X represents the ring members required for completing a benzoxazole.benzothiazole. benzoselenazole or quinoline ring. which may besubstituted. e.g. benzothiaZole. 4-chlorobenzothiazole. 5chlorobenzothiazole.

o-chlorobenzothiazole. 7-chlorobenzothiazole. hbromobenzothiazolc.5'iodobenzothiazole. (v iodobenzothiazole. 4-methylbenzothiazole. 5-methylbenzothiazolc. o-meth ylhenzothiazole. 5,o-dimethylbenzothiazole.4-phenylbenzothiazole. 5- phenylbenzothiazole. o-phenylbenzothiazole. 5hydroxybenzothiazole, o-hydroxybenzothiazole. 4- methoxybenzothiazole.5-methoxybenzothiazole. 6- rnethoxybenzothiazole. 5ethoxybenzothiazole.6-

benzoxazole. 5 -chlorobenzoxazole. bchlorobenzoxazole. S.6-dimethylbenzoxazole, 5- phenylbenzoxazolc. 5-hydroxybenzoxazole. 5methoxybenzoxazole. 5-phenylbenzoxazole. 5- hydroxybenzoxazole.5-methoxybenzoxazole. S-

ethoxybenzoxazole, o-diall;ylaminobenzoxazole, S-earboxybenzoxazole,5sulphobenzoxazole. sulphonamidobenzoxazole. 5-carboxyvinylbenzoxazolequinoline. 3-methylquinoline, S-methylquinoline. 7

methylquinoline. 8-methylquinoline. 6- chloroquinoline.8-chloroquinoline. 6- methoxyquinoline, o-ethoxyquinoline. 6-hydroxyquinoline. S-hydroxyquinoline or S-oxo-5,o.7,S-tetrahydroquinoline;

R or R represents a saturated or olefinically unsaturated aliphaticgroup with preferably up to 5, in particular up to 3 carbon atoms. whichgroup may be substituted in one or more positions. cg. with halogen suchas fluorine. chlorine or bromine. hydroxyl. carboxyl. esterifiedcarboxyLcarbamoyl. sulpho. sulphonamido. sulphato, thiosulphato orphosphoric acid groups;

R represents alkyl with preferably up to 3 carbon atoms, cycloalkyl suchas cyclopentyl or cyclohexyl or phenyl;

n O or l and Z represents any anion such as chloride, bromide, nitrate,iodide. phosphate. fluoride. perchlorate, acetate. tosylate. sulfate.methylsulfate. oxalate. lactact or benzoate; it may be absent in caseswhere a molecule already contains an acidic group. so that a bctaine ispresent. Quinoline dyes of the following formula are preferred:

R. R X and Z have the meanings indicated above and R* represents l) ahydrogen. (2) halogen such as fluorine. chlorine. bromine or iodine, (3)alkyl or (4) an alkoxy group both of which preferably contains up to 3carbon atoms and may be substituted. e.g. with carboxyl. sulfo orhalogen Meso-substituted cyanine dyes of the following for- 5 mula arealso particularly suitable:

in which R R R and Z have the meanings indicated above and X representsa benzoxazole, benzothiazole or benzoselenazole ring which may besubstituted, eg. those already mentioned above.

The following are examples of suitable compounds:

1 (III) 5 b-cfi=-ca=c z n' \n' I a a on N C\N I I 9 c a so CH Cl Me N II 02H5 3 1- CH Na o f 9 9 c a so 63116503 it @Q i) A M ca c N J G) e9 ca coon ocH A 5 gee U C CH c G n co \N J 1 CZH5 3 1-1 A 6 Q: g c W5 i o HC cl (3H 1 o H c C2H5 2 5 3 H c N N I I H c n -CH=CCH=C E) c1 01 3 A sEH2 (3H2 a E 2, OOOH 00 The supersensitizers used are styryl dyespreferably those of the following formula:

X ,X CE ca n 6 S-methylthiazole, 4,5-dimethylthiazole, 4-phenylthiazole, 5-phenylthiazole, or 4,5- diphenylthiazole,benzothiazole (e.g. benzothiazole, 4-chlorobenzothiazole,S-chlorobenzothiazole, 6- chlorobenzothiazole, 7-chlorobenzothiazole, 6-bromobenzothiazole, 5-iodobenzothiazole, 6- iodobenzothiazole,4-methylbenzothiazole, 5-

methylbenzothiazole, o-methylbenzothiazole, 5,6'dimethylbenzothiazole,4-phenylbenzothiazole, 5-

phenylbenzothiazole, o-phenylbenzothiazole, 5- hydroxybenzothiazole,fi-hydroxybenzothiazole, 4- methoxybenzothiazole,S-methoxybenzothiazole, 6- methoxybenzothiazole, S-ethoxybenzothiazole,6-

ethoxybenzothiazole, 5,6-dimethoxybenzothiazole, 5,G-methylen-dihydroxybenzothiazole, 5- diethylaminobenzothiazole, 6-diethylaminobenzothiazole, -nitrobenzothiazole, 5-carboxybenzothiazole,S-sulfobenzothiazole, 6 cyanobenzothiazole,5'trifluoromethylbenzothiazole, S-benzoylbenzothiazole,tetrahydrobenzothiazole or 7-oxotetrahydrobenzothiazole, naphthothiazole(e.g. naphtho[l,2-d]thiazole, naphtho-[2,l-d]thiazole, 7-methoxynaphtho[ 2, l -d lthiazole or 8- methoxynaphtho[2,l-d]thiazole),selenazole (e.g. 4- methylselenazole or 4-phenylselenazole),benzoselenazole (e.g. benzoselenazole, S-chlorobenzoselenazole,5.6-dimethylbenzoselenazole, 5- hydroxybenzoselenazole,S-methoxybenzoselenazole,

dlselenazole, oxazole (e.g. oxazole, 4-methyloxazole, 4-phenyloxaz0le or4,5-diphenyloxazole). benzoxazole (e.g. benzoxazole, Schlorobenzoxazole.6- chlorobenzoxazole, 5,b-dimethylbenzoxazole, 5- phenylbenzoxazole,5-hydroxybenzoxazole, 5 methoxybenzoxazole, 5-ethoxybenzoxazole, 6-dialkylaminobenzoxazole, 5-carboxybenzoxazolc, 5- sulfobenzoxazole.sulfonamidebenzoxazole or 5-carboxyvinylbenzoxazolc). naphthoxazole(e.g. naphtho[ l ,2-d ]-oxazole, naphtho[ 2.1 -d ]oxazole ornaphtho[2,3-d]-oxazole), 3,3-dialkylindolenine (e.g.3,3-dimethylindolenine, 3.3,S-trimethylindolenine or3,3-dimethyl-5methoxyindolenine). Z-pyridine (e.g.

pyridine, 3-methylpyridine, 4-methylpyridine. 5- methylpyridine,-methylpyridine, 3,4- dimethylpyridine, 3,5-dimethylpyridine. 3.6-dimethylpyridine, 4,5-dirnethylpyridine. 4,6-

dimethylpyridine, 4-chloropyridine, S-chloropyridine, 6-chloropyridine,3-hydroxypyridine, 4- hydroxypyridine, S-hydroxypyridine,3-phenylpyridine, 4-phenylpyridine or -phenylpyridine), 4-pyridine (e.g.Z-methylpyridine, 3-methylpyridine, 2,3- dimethylpyridine,2,5-dimethylpyridine, 2,6- dimethylpyridine, Z-chloropyridine,3-chloropyridine, 2-hydroxypyridine, or 3hydroxypyridine), 2-quinoline(e.g. quinoline, 3-methylquinoline, S-methylquinoline,

7-methylquinoline, 8-methylquinoline, 6- chloroquinoline,8-chloroquinoline, 6- methoxyquinoline, fi-ethoxyquinoline, 6-hydroxyquinoline, S-hydroxyquinoline or 5-0xo-5,6,7,S-tetrahydroquinoline), 4-quinoline (eg, quinoline,b-methoxyquinoline, 7-methylquinoline or 8- methylquinoline),isoquinoline (e.g. isoquinoline or 3,4dihydroisoquinoline), thiazoline(e.gl thiazoline or 4-methylthiazoline), oxazolone or ring members basedon pyrroline, tetrahydropyridine, thiadiazole. oxadiazole, pyrimidine,triazine or benzothiazine, benzotriazole, pyrimidone 0r thiopyrimidone.The aryl groups and the heterocyclic groups may in turn be substitutedin any way desired, e.g. by alkyl groups which preferably have up to 3carbon atoms such as methyl or ethyl or with halogen such as chlorine orbromine, hydroxyl, alkoxy with preferably up to 3 carbon atoms such asmethoxy or ethoxy, hydroxyalkyl, alkylthio, aryl such as phenyl oraralkyl such as benzyl, amino, substituted amino or nitro.

or tetrahydrobenzoselenazole), naphthoselenazole (e.glnaphtho[l,2-d]selenazole or naphtho[2,l- The following are examples ofsuitable compounds:

\ N; CH CHN(CH B2 ,S-ca=cn N(CH) B 5 i B e ;C CH CH- N(C H r N o i CZH(ontinued NA CH CH- N(CH {1H B l 1C CH CH. -"*N(CH) N 5 2 Q) C 8 Thepreparation of the supersensitizable sensitizers is carried out by knownmethods. cg. by reacting 2 alkylthiosubstituted hererocyclic quaternarysalts with Z-methylsubstituted heterocyclic quaternary salts, mercaptansand acids being split off in the process.

Reference may be made to German Pat. Specifications No. 710,748 and917,330 and to British Pat. Specifications No. 742.112 and 1,253,839.The same applies to styryl dies, the preparation of which has beendescribed in German Pat. Specifications No. 394,744 and 395,666.

The sensitivity enhancing effect of the supersensitizers is particularlysurprising in view of the fact that solarization. which is based on thedestruction of latent image nuclei by positive holes or photolyticallyformed halogen, is suppressed by various halogen acceptors or positivehole acceptors. It was therefore to be expected that the destruction offog nuclei in direct positive emulsions, which is analogous to theprocess of solar ization, would also be suppressed by supersensitizerssince these compounds may be regarded as positive hole traps. Theexactly opposite effect, however. is produced in this invention.

The fogged direct positive silver salt emulsions preferably containsilver halides, e.g. silver chloride or silver bromide, more preferablysilver bromide, optionally with a small proportion of silver iodidewhich may be up to 10 mols percent. The binders used for the emulsionlayer may be the usual hydrophilic filmforming substances such asproteins particularly gelatine, alginic acid or its derivatives such asesters, amides or salts, cellulose derivatives such ascarboxymethylcellulose, starch or its derivatives or hydrophilicsynthetic binders such as polyvinyl alcohol, partly saponified polyvinylacetate, or polyvinylpyrrolidone. The hydrophilic binders of the layersmay also be mixed with solutions or dispersions of other syntheticbinders such as homopolymers or copolymers of acrylic or methacrylicacid or their derivatives such as esters, amides or nitriles or vinylpolymers such as vinyl esters or vinyl ethers.

The fogged silver salt emulsion layers are applied to the usual supportlayers, eg. glass or foils of cellulose esters such as cellulose acetateor cellulose acetobutyrate or foils of polyesters. particularly ofpolyethylene l i c t ;C ca on --n(cn J 9 teraphthalate or polycarbonate,especially those based on bisphenylolpropane. Other materials suitablefor use as support layers are baryta paper or paper which has beenlaminated with polyolefins such as polyethylene or polypropylene.

The fogged silver halide emulsions used for the invention preferablyhave a narrow range of grain sizes; finegrained emulsions areparticularly suitable but the invention is not restricted to these typesof emulsions, which are described in British Pat. Specification1,027,146. The grain size distribution is preferably such that at leastby weight of the silver halide grains do not deviate from the averagegrain diameter by more than 40% The surface fogging of the silver halidegrains in the photographic direct positive emulsions according to theinvention is carried out in known manner for example by treating theemulsions with reducing agents, preferably in the presence ofwater-soluble salts of metals which are more electropositive thansilver. Suitable reducing agents are, e.g. tin(Il) salts such as tintIl)chloride. hydrazine or hydrazine compounds, sulfur compounds such asthiourea dioxide or phosphonium salts such astetra(hydroxymethyl)-phosphonium chloride. Suitable compounds of metalswhich are more electropositive than silver are, for example, thefollowing noble metal salts: Gold salts such as potassium chloroaurate,gold(lll) chloride, salts of rhodium, platinum or palladium such asammonium hexachloropalladate and iridium salts such as potassiumchloroiridate. Emulsions of this kind have been described in BritishPat. Specification No. 723,019 and in German Offenlegungsschrift No.1,547,790.

The concentration of the reducing agents or noble metal salts used forfogging may vary within wide limits. It is generally sufficient to useconcentrations of 0.05 to 50 mg of reducing agent and 0.1 to 15 mg ofthe noble metal salts per mol silver salt. If the emulsions have beentoo heavily fogged, they may subsequently be treated with a bleachingagent in known manner so that the direct positive emulsions can beadjusted to the optimum sensitivity to light.

According to a preferred embodiment of this invention, the fogged directpositive silver halide emulsions used contain ripening nuclei in theinterior of the silver halide grain. As described in the publication ofE. Moisar and S. Wagner in Berichte der Bunsengesellschaft furphysikalische Chemie" 67 (1963). 356 359. the photoelectrons which areformed in the primary process and prevent destruction of the developablefog nu clei at the surface of the grain are thereby trapped in theinterior of the grain. The preparation of such emul sions with acomposite grain structure has been described in British Pat.Specification No. l.027.l46 and in German Offenlegungsschrift No.1.597.488. The formation of ripening nuclei in the interior of the grainis carried out in known manner by chemical sensitization with noblemetal compounds. in particular with gold salts or iridium salts or withsulfur compounds such as thiosulfate or a combination of treatment withnoble metal salts and sulfur compounds.

The sensitizers which are capable of being supersensitized are presentin the usual concentrations in the emulsion. Suitable concentrations aree.g. 50 mg to 2 g, preferably 0.1 to 0.5 g, per mol of silver salt. Theconcentration of supersensitizing styryl compound is 5 to mols percent.based on the quantity of sensitizing dye used. The addition ofsensitizers or supersensitizers to the direct positive emulsions iscarried out in the same way as the addition to negative emulsions.preferably shortly before the emulsions are cast from alco holic oraqueous solutions.

Other direct positive emulsions which are suitable for this inventionhave been described in German Pat.

groups. Compounds ofthis kind have been described in' the article byBirr, Z.Wiss.Phot. 47 2 58 (I952). Other suitable stabilizers includeheterocyclic mercapto compounds. e.g. phenylmercaptotetrazole. quaternary benzothiazole derivatives. or benzotriazole.

The emulsions may be hardened in the usual manner. for example withformaldehyde or halogenated aldehydes which contain a carboxyl group.such as mucobromic acid. diketones. methane sulphonic acid esters ordialdehydes.

The emulsions according to the invention may also contain the usualcolor couplers which yield image dyes by reacting with the oxidationproducts of colour forming developers. in particular those of thepphenylenediamine series. The usual color couplers are suitable for thispurpose, e.g. pyrazolone couplers or couplers of the naphthol series orthe benzoyl acetanilide series. The color couplers may be added to theemulsion layers in the form of solutions or dispersions in known manner.The emulsions according to the invention may also contain dyes which areattached to a developer molecule and which are capable of diffusingimagewise into a receptor layer from the exposed and thereforenon-developable image areas. The dyes may also be in the form ofdiffusion resistant compounds from which they are liberated by theproduct of oxidation of the developer so that they can diffuse into animage receptor layer. Lastly, the emulsions may contain dyes which aredestroyed imagewise in the devel' oped. i.e. exposed areas by reductionin a bleaching process following development. These dyes are preferablyazo dyes.

Example 1 Preparation of the emulsion:

1800 ml of 3N silver nitrate solution and 1800 ml of 3N potassiumbromide solution are introduced into i500 ml of a 5% gelatine solutionby means of dosing pumps at the rate of 800 ml/hour each at 60C.Precipitation is stopped when 20% of the total quantity of the twosolutions has been added to the gelatine solution. After the addition of5 ml of a 10 molar solution of Na [Au(S O the mixture is digested for 30minutes at 60C and thereafter precipitation is completed. The emulsionis solidified after the addition of I20 g of gelatine and then washed inthe usual manner.

After washing, the resulting silver halide emulsion. which containsripening nuclei in the interior of its grains. is fogged by treating itfor one hour at 50C with l5 cc of a 0.1?! aqueous solution of gold(lll)chloride and 0.3 g of hydrazine hydrate per mol of silver halide.

The emulsion has a very narrow range of grain sizes. The length of theedge of the cubical silver halide grains is 0.35 pm. The emulsion issubsequently diluted to a concentration of about 20 g of silver bromideand 50 g of gelatine per litre with gelatine solution.

This diluted emulsion is divided into several portions or individualsamples and to each sample there are added, in addition to the usualhardeners and wetting agents. 0.35 g of a supersensitizable sensitizerper mol of silver bromide and. in some cases. 0035 g of supersensitizingadditive per mol of silver bromide. The emulsions are then cast on acellulose acetate support layer and exposed behind a spectral wedge.They are then developed with a p-methylaminophenolhydroquinone developerfor 5 minutes at l8"Cv The substances added to the individual samplesare summarized in the table below.

The results of the sensitomeric determinations are represented in theattached FIGS. 1 to 19. These fig- Example 2 A silver iodobromideemulsion was prepared as de scribed in the first paragraph of Example I,but after preparation of the internal nuclei which act as electrontraps. a shell of AgBr/l was precipitated by running in simultaneously asolution of AgNO and a solution of KBr containing 3 mols percent of Kl.Subsequent treatment was the same as that described in paragraph 1 ofExample I,

500 ml portions of the fogged emulsion described above were treated witha quantity of sensitizer corresponding to 0.35 g of dye per mol ofAgBr/l, either alone or together with a supersensitizer in an amount of0.035 g per mol ofAgBr/l. The scnsitizers and supersensitizers used areshown in the table below. Subse quent treatment was the same asdescribed in Example I. The spectrograms represented in FIGS. 20 to 23demonstrate the sensitivity increasing influence of the supersensitizer.

Each 500 g portion of the emulsion prepared according to Example 1 wassensitized with 0.35 g ofsensitizer A l mol of AgBr. In addition, 4.5 gof a 3-acylaminol-phenyl-pyrazolone coupler were added to the emulsionas magenta coupler.

0.035 g of B 1 /mol of AgBr was added to one 500 g portion of the aboveemulsion before the addition of the colour coupler. After exposurebehind a spectral wedge, the emulsions were developed in a conventionalcolour developer. The spectrograms in FIGS. 24 and 25 demonstrate thesensitivity increasing effect of the su persensitizer.

We claim:

1. A photographic direct-positive material containing at least onedirect-positive fogged silver halide emulsion layer, the silver halidegrains of said emulsion layer contain electron traps. the said emulsioncontaining a super-sensitizing combination comprising a symmetrical orunsymmetrical cyanine dye of the following formula:

in which X the ring members required for completing a henzooxazole,benzothiazole, benzoselenazole or quinoline ring; R or R a saturated orolefinically unsaturated ali- 5 phatic group;

R 2 alkyl with up to 3 carbon atoms cycloalkyl or phenyl; n (l or 1;

Z" 2 any inorganic or organic anion; and a supersensitizing styrylcompound of the following formula:

grains ofthe direct positive silver salt emulsion contain internalripening specks.

1. A PHOTOGRAPHIC DIRECT-POSITIVE MATERIAL CONTAINING AT LEAST ONE DIRECT-POSITIVE FOGGED SILVER HALIDE EMULSION LAYER, THE SILVER HALIDE GRAINS OF SAID EMULSION LAYER CONTAIN ELECTRON TRAPS, THE SAID EMULSION CONTAINING A SUPER-SENSITIZING COMBINATION COMPRISING A SYMMETRICAL OR UNSYMMETRICAL CYANINE DYE OF THE FOLLOWING FORMULA:
 2. The photographic material of claim 1, wherein the cyanine dye has the following formula:
 3. The photographic material of claim 1, wherein n stands for 1 and X represents a benzoxazole, benzothiazole or benzoselenazole ring.
 4. The photographic material of claim 1, wherein the grains of the direct positive silver salt emulsion contain internal ripening specks. 